Effect of moderate alcohol consumption on liver enzymes increases with increasing body mass index.

Background: Although both ethanol consumption and overweight alter the activities of hepatic enzymes in circulation, the differentiation of an alcohol or nonalcohol basis for such changes remains problematic. The magnitude of alterations occurring among moderate drinkers has remained obscure.

Objective: We examined the links between moderate ethanol consumption, body mass index (BMI; in kg/m(2)), and liver enzymes.

Design: Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and gamma-glutamyltransferase (GGT) were recorded from 2,164 apparently healthy participants (1,028 men, 1,136 women) reporting either no alcohol (abstainers) or <40 g ethanol consumption per day (moderate drinkers). The study population was further classified according to BMI as follows: <19 (underweight), > or =19 and <25 (normal weight), > or =25 and <30 (overweight), and > or =30 (obese).

Results: Serum ALT (P < 0.05) and GGT (P < 0.001) but not AST (P = 0.805) activities in moderate drinkers were higher than those in abstainers. For all enzymes, a significant main effect was observed of increasing BMI, which was more striking in moderate drinkers than in abstainers. Tests of between-subjects effects indicated significant interactions with sex and drinking status, although not with sex and BMI.

Conclusions: The effect of moderate alcohol consumption on liver enzymes increases with increasing BMI. These findings should be considered in the clinical assessment of overweight alcohol consumers and in the definition of normal ranges for liver enzymes. These results may also help to develop new approaches for examining patients with fatty liver induced by either ethanol or adiposity.